(i) Field of the Invention
This invention relates generally to processes for stabilizing metal alkoxides to retain the same in fluid form during shipment and storage prior to use. It also relates generally to coating compositions comprising metal alkoxides and phosphorus-containing compounds as functional components. More particularly, it relates to aluminum alkoxides containing 2 to 5 carbon atoms per alkoxy radical which are stabilized against solidification/crystallization by the addition of minor amounts of specific organo phosphates. It also relates to the novel products thereby obtained.
(ii) Prior Art
Metal alkoxides are extremely old in the art. An excellent concise summary of their properties, end-uses, and methods of preparation is found in Kirk-Othmer's third Edition 1978, ISBN 0-471-02038-0, "Encyclopedia of Chemical Technology", Vol. 2, at pages 1-17 entitled "Alkoxides, Metal" by D. Bretzinger and W. Josten.
U.S. Pat. No. 2,687,423 (Mesirow) relates to stabilizing certain supercooled liquid lower alkyl aluminum alkoxides (having 2 to 4 carbon atoms in the alkoxide radical) against solidification, by the addition of critical amounts (5 to 40 wt. %) of aluminum trisecondary butoxide, Al(OCHCH.sub.3 C.sub.2 H.sub.5).sub.3, itself an aluminum alkoxide. Mesirow theorizes that some interchange of alkoxide radicals may take place, particularly when the mixture is heated (see col. 3, lines 35 -60).
A computer search of Chemical Abstracts since 1967 for references relating to both metal alkoxides and phosphorus-containing compounds turned up only the five following references.
U.S. Pat. No. 4,287,131 (Langer et al.) discloses an invention wherein a metal alkoxide (particularly an aluminum alkoxide) "is contacted with phosphorus pentoxide in an inert liquid organic medium resulting in the production of an organo polyphosphate coordination complex with a metal compound. The resulting compounds have been found to be useful as polymer additives, corrosion inhibitors for functional fluids and as fire retardants for cellulosic materials." However, Langer does not relate to the use of an organic phosphorus compound as raw material. Nor does Langer relate to a product that is a liquid (but rather a gel).
U.S. Pat. No. 3,655,423 (Lin et al.) particularly "relates to a process for applying organic coating compositions or organic films such as siccative coatings, dyes, adhesives and the like to substrates which have been subjected to a low oxidation state phosphorus compound which can be prepared by reacting elemental phosphorus with a nucleophilic reagent or organometallic compound." Lin does not relate to the use of a phosphorus compound having an oxidation state of 5.
Japanese Pat. No. 7411759 (Oda et al.) relates to the catalytic polymerization of alkylene oxide. According to the CA Abstract, the catalyst may be alkoxides-phosphorus halides; . . . phosphorus halide; . . . aluminum isopropoxide." It appears to be less relevant than the aforementioned art.
Japanese Pat. No. 7310958 relates to the catalytic polymerization of epoxides. According to the CA Abstract, the catalyst may be metal alkoxides or alkoxide halides containing phosphorus esters. The only metals listed in the abstract are titanium, zirconium and hafnium. Aluminum is not listed therein. Accordingly, it also appears to be less relevant than the aforementioned prior art.
In addition, U.S. Pat. No. 3,904,550 (Pine) is of interest in that it relates to:
"the reaction in aqueous medium of aluminum alkoxide with a phosphorus-containing acid or soluble salt thereof at an aluminum alkoxide/phosphate ion molar ratio in the range of 26:1 to 1.2:1, said phosphorus-containing acid having the formula: ##STR2## wherein R respresents a hydroxyl group, hydrogen or a hydrocarbon radical containing from 1 to 12 carbon atoms" (see Pine, claim 1).